1. Field of the Invention
This invention relates to a device for producing spinning yarn, and more particularly to a device for twisting an untwisted filament sliver drafted by a draft device to produce spinning yarn.
2. Description of Related Art
Conventional spinning frames are generally divided into three types: the ring type, the open end type and the pneumatic type. Among these three types, spinning frames of the pneumatic type have been developed in recent years and have a high speed spinning faculty, as high as several times the spinning faculty of spinning frames of the ring type.
An exemplary one of such spinning frames of the pneumatic type is disclosed in Japanese Patent Publication No. 53-45422 (U.S. Pat. No. 4,112,658). In the disclosed arrangement, two air injecting nozzles are disposed in contiguous relationship to a draft device for producing compressed air flows which whirl in opposite directions to act upon a sliver coming out from the draft device. The sliver is twisted by the second nozzle, and the thus twisted sliver is ballooned by the first nozzle. By such ballooning of the sliver, some fibers of the sliver are wrapped on other fibers. Then, when the sliver passes the second nozzle and is thereupon untwisted by the same, the fibers are wrapped tightly around the other fibers. In this manner, spinning yarn is produced.
Detailed examination of yarn produced by such a pneumatic spinning frame as described above has revealed that the yarn is bundled spinning yarn, wherein some fibers are wound spirally around other untwisted or loosely twisted core fibers. The ratio in quantity between such core fibers and wound fibers, the winding manner of fibers and other yarn characteristics can be altered to some extent by variously changing operating conditions. Physical properties of the yarn, such as strength, can also be altered accordingly.
However, where the length of fibers is relatively long, it is difficult to stabilize the behavior of wrapped fibers on a pneumatic spinning frame. Further, since the pneumatic spinning frame involves two nozzles, it consumes a large amount of compressed air and has a correspondingly high energy cost. It has a further disadvantage in that its ability to spin long fibers, such as fibers of wool, is not very high.
The present invention has been made in view of such circumstances as described above, and it is an object of the present invention to eliminate such drawbacks as described above by providing a novel spinning apparatus which can replace such a conventional pneumatic spinning frame as described above.